One of the methods for forming wiring or contact hole patterns of semiconductor devices is pattern forming methods using block copolymers. For example, it is possible to use a pattern formed by a conventional optical lithography technique as a guide layer and forma regular pattern of smaller dimensions using phase separation of a block copolymer. This technique is called a directed self-assembly (DSA) technique.
However, polymer patterns formed by a DSA technique do not have sufficient dry etching resistance. Thus, for dry etching processing with a polymer pattern formed by a DSA technique as a mask, there is a method of selectively forming a protective film such as an oxide previously on the pattern. In this case, although dry etching resistance is improved, a process step of forming a protective film is additionally required. The additional process step makes a manufacturing process complicated and expensive.